<p>
Numbers are not self-explanatory, they only are made of a value, which does not explain their purpose.
Moreover, if the same number should be consistently used in multiple places, using a constant will ensure that all occurrences are updated at once.
</p>

<p>The following code:</p>

<pre>
netSalary = 0.85 * grossSalary;  // Non-Compliant - where does 0.85m come from, what does it mean?
</pre>

<p>should be refactored into:</p>

<pre>
const double Rate = 0.85;        // Compliant - it's now clear what the 0.85m is
netSalary = Rate * grossSalary;  // Compliant
</pre>
